Footwear insoles, also called podiatric orthoses or orthotic shoe inserts, are used to support the human foot in a footwear, and have been known for quite some time in the field. These devices consist usually of a moulded blank shell formed monolithically from a resilient semi-rigid sheet material, usually a synthetic plastic material. Orthotics are characterized by the fact that they properly adjust the orientation of a handicapped person's foot during gait, for controlling its motion in view of mitigating the adverse effects of podiatric anomalies. Examples of such insoles include U.S. Pat. No. 4,756,096 issued Jul. 12, 1988 to Grant Meyer, and U.S. Pat. No. 4,338,734 issued Jul. 13, 1982 to Apex Foot Products Corp.
Some of these orthoses do not form full plantar shells. For instance, U.S. Pat. No. 5,058,585 issued Oct. 22, 1991 to Michael Kendall discloses a generally open orthotic shoe insert forming a curved wedge having a generally open hook-like shape. This insert is said to control foot motion during gait, and includes a heel portion, adapted to engage the sides of the heel, a middle portion, adapted to engage the plantar side of the medial portion of the foot longitudinal arch, and a front portion adapted to engage the plantar side of the user's forefoot to a level just distal to the first and second metatarsal heads. Such an orthosis is claimed to be self-adjusting.
U.S. Pat. No. 5,174,052 issued Dec. 29, 1992 to Harold Schoenhaus and Richard Jay, discloses an orthotic device having a deep heel seat to cup the calcaneus. High medial and lateral flanges define a bottom forwardly opening notch. This orthotic device is designed to prevent hyperpronation of the human foot.
Problems with these known orthotic devices include:
(a) they take too much volume in the footwear, so the foot is uncomfortably compressed inside the footwear; PA1 (b) they often are undesirably allowed to accidentally shift in position inside the footwear, especially during prolonged gait. PA1 an arched intermediate portion for complementary vertical resilient spring-back engagement against the foot arch plantar portion; PA1 a rear end portion comprising spaced-apart inner and outer rearwardly-extending resiliently deformable arms for partial resting abutment of said heel onto said arms, said arms defining at their rear end portions a rearwardly-opened notch therebetween for enabling partial engagement of the heel in said notch, said inner and outer arms respectively forming upwardly arcuate inner and outer flanges opposite said notch, for complementary engagement partly around the heel portion of the foot; PA1 a front end portion integrally frontwardly extending from said intermediate portion and for complementary engagement near the anterior metatarsal plantar region of the foot said front end portion having a sinuous front edge comprising a number of frontwardly-facing arcuate concavities each for registering engagement thereagainst by a corresponding one of the metatarsal anterior portions of that person's foot, allowing distinct metatarsal support and articulate positional self-adjustment of said orthosis inside the footwear in addition to helping to prevent plantar lesions;
The Schoenhaus patent is a good example of an orthosis which takes too much volume. The rear portion of this U-shaped orthosis will effectively require space under and around the heel portion of the foot, since the heel rests on the orthosis and the orthosis moreover partially surrounds the heel. The person wearing a shoe in which is provided the Schoenhaus orthosis is likely to be less comfortable in the shoe, since the foot will be raised in the shoe by the orthosis; considering that shoes are not designed for feet having a thickness which is abnormally increased relative to the usual proportional dimension of the feet, the wearer of the shoes fitted with the Schoenhaus orthoses is likely to be uncomfortable.
Another problem with the Schoenhaus orthosis is that the frontwardly-opened notch in the orthosis main body may effectively allow the foot to tilt, pivot and rotate around the heel portion, due to the flexibility conferred to the orthosis by the frontwardly-opened notch. Indeed, rotation and pivotal movement of the foot is achieved at the ankle, located substantially over the heel portion of the foot. Allowing the two frontwardly extending arm portions of the orthosis to laterally flex under load, effectively counteracts the results which are desired by wearing an orthosis, which is to prevent undesirable positions of the foot, some positional deficiencies being achieved under accidental tilting, rotating or pivotal movements of the foot which may be allowed by the flexibility of the frontwardly extending arms of the Schoenhaus orthosis.
Yet another disadvantage of the Schoenhaus patent is that weaker support under the foot arch is provided, since the opened notch is located under the foot arch.
U.S. Pat. No. 4,686,993 issued in 1987 to Grumbine shows an orthosis which has an arch support portion and a rear slightly concave heel seat which has a central opening in which the heel is partially engageable. The rear opening allows a lesser overall thickness of the orthosis rear portion, but the support offered by the Grumbine orthosis is not sufficient, especially due to a lack of lateral support.
As with most prior art orthoses, both the orthoses disclosed in the Grumbine and the Schoenhaus patents also have the important disadvantage of being allowed to accidentally move or shift inside the shoe, especially during prolonged gait, since no means are provided for positional self-adjustment of the orthosis inside the shoe. Thus, under repetitive or sudden foot movement inside the shoe, the orthosis may be allowed to shift inside the shoe, which of course results in undesirable discomfort for the wearer.
U.S. Pat. No. 1,974,161 issued in 1932 to Riley and U.S. Pat. No. 2,498,624 issued in 1948 to Skinner both disclose orthoses having a rear heel notch, which allows the rear portion of the shoe insole to take up less volume in the rear portion of the footwear. However, no lateral support whatsoever is provided by the Riley and Skinner orthoses at the rear portion of the foot, and thus no accidental insole shifting or foot hyperpronation is prevented with these insoles.
A problem associated with most orthoses is that lesions are often created on the front plantar portion, under the metatarsal heads or rearwardly near them, by the front edge of the orthosis or of the insole. Indeed, the orthoses or insoles often extend short of the toes, as shown in the Grumbine, Skinner, Riley and Schoenhaus patents. Although the orthosis is expected to gradually frontwardly slope towards the shoe's sole so as to form therewith an almost continuous surface under the metatarsal head region, the reality is otherwise: the frontmost edge of the orthosis often repetitively raises during gait spacedly above the shoe's sole, and under repetitive contact with the foot plantar surface, is likely to cause lesions and injure the foot plantar metatarsal region. Moreover, the foot is often not allowed to recover from these lesions, since the already injured plantar foot portion continues to suffer lesions from its subtle contact with the linear front edge portion of the orthosis under continued use of the orthosis.